The disbudding (nipping) x genotype interaction demonstrates different perennial habits in castor-oil plant (Ricinus communis L.).

In castor-oil plant the perennial habit contrasts with the combine harvester. A hypothetical non-branching annual castor plant is based on the stop of the meristem activity in the axillary buds and/or in the cambium. To investigate the relationship between the cambial activity and the axillary bud outgrowth, an experiment on the axillary bud excision was carried out in the field with 64 inbred lines. The stems of treated plants were disbudded, while, as control, the same number of plants was untreated. At the harvest of the first raceme, the treated plants had obviously only the main stem whereas the control plants resulted normally branched. The disbudding treatment heavily affected the stem diameter and interacted with the genotypes. The seed production and the 1000-seed weight were significantly affected by the disbudding treatment. This research, aimed at solving a cultivation problem, can also contribute to better know the semelparity in plants.